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The Effect of Soil Potassium Levels on Yield, Lodging, and Mineral Composition of Corn¹

ABSTRACT

Five corn hybrids (three single crosses and two double crosses) were grown on a soil low in exchangeable potassium. Four potassium fertility levels were used. K, Ca, Mg, and P were determined on leaf samples collected periodically throughout the growing season. Root lodging and stalk breakage were also determined periodically. A significant yield increase from the first increment of K₂O was obtained, but no further increase was obtained from additional increments. Significant yield differences among corn hybrids were obtained. Potassium fertilization significantly decreased both root lodging and stalk breakage. The corn hybrids were found to differ significantly in their root lodging and stalk breakage characteristics.

The potassium content of the plant increased with increased rates of potassium fertilization. The maximum potassium content of the plant was observed during the early stages of plant growth and the potassium content decreased percentagewise as the plant neared maturity. The calcium and magnesium contents of the leaf tissue were generally inversely related to the potassium content of the plant. The phosphorus content was unaffected by the potassium fertility treatments. The milliequivalents of total cations (K, Ca, Mg) per 100 g. of over-dry tissue (1) decreased at a given stage of plant growth as the rate of potash fertilization increased, (2) increased with age of plant at the lower potassium levels, and (3) remained essentially constant throughout the life of the plant at the highest potassium level. The sum of the percent K, Ca, and Mg content of the plant was essentially a constant at all stages of growth.

¹ Contribution from the Department of Agronomy, University of Tennessee Agr. Exp. Sta. This work was supported in part by a grant from the American Potash Institute. Presented before Div. IV, Soil Science Society of America, Nov. 15, 1956 at Cincinnati, Ohio.

² Formerly graduate fellow, now Assistant Agronomist, Georgia Exp. Sta., Experiment, Georgia, and Agronomist, respectively.

Received for publication September 11, 1956. Accepted for publication December 20, 1956.